Telegraph transmitter



May 22, 1951 R. H. DUNN ETAL 2,553,556

' TELEGRAPH TRANSMITTER Filed Dec. 14, 1948 4 Sheets-Sheet 1 A TTOPA/E) y 22, 1951 I R H. DUNN ETAL I 2,553,556

TELEGRAPH TRANSMITTER Filed D'ec. 14, 1948 4 Sheets-Sheet 2 F/GZ A T TOP/VF) May 22, 1951 R. H. DUNN ETAL TELEGRAPH TRANSMITTER 4 Sheets-Sheet 4 Filed Dec. 14, 1948 A TTOIP/VEY Patented May 22, 1951 LA ENT O F C -TELEGRAPH TRANSMITTER H Roland. Harris'Dunn and Frederick William War- I den, .London England; assignors to International Standard Electric Corporation, New York, N, Y., .a corporation of Delaware Ap li at on December 14, 1948, Serial No. 65,092

In Great Britain December 17, 1947 This inventionrelates to teleprinter trans- .mitters. 1- r l l In the co-pending application of Eric M. S.

McWhir'ter bearing SerialNo. 744,009, filed on April 25, 1947 now Patent No. 2,504,999, patented April 25, 1950, there has been described; and claimed a transmitterefor a telegraph code in which the time base consisted of a chain of electronic-devices and means for causing the said vices to be conducting sequentially for equal periods of-time..

In the embodiment described in said applica- .tion the electronic devices were cold-cathode gas ,f lled tubes,-each having acathode, a control electrode and an anode, there being one of saidtubes 1.5 101- the start .e1ement,;one tube for Jeach'of the code elements and. at least one tubeifor a stop element. Impulses were applied to the, control ,electrodes of all the tubes and when'one tube was madeconducting a-bias was applied to the next.

.tube in the chainto render that'tubecon ducting when the next impulse was applied. The anodes of the tubes were connected over the marking and spacing windings of a telegraph relay, these connectionsbeingchanged accordin to the charactel-required to be sent. I s

7 The circuits according to the present invention use the arrangement of a time base generated by a series of electrondischarge devices'rendered conducting sequentially in the manner de-' scribed and claimed in the above-mentioned as plication. Each electron dischargedeviceis allotted to'a particular kind of element (marking or spacing), and these devices are arranged in a 'kind of tree formation so that commencing from a device individual to the first element to be transmitted, a chain of devices'individual to the selected combination of elements is transmitted by the sequential operation of the tubes in said chain. l I I "Accordingto the present invention a transmitter for transmitting anyone of a plurality of code combinations each consisting of the same number of successive elements of marking and "spacing condition comprises spacing electron discharge devices connected to transmitting meanss in such manner that whena device becomes conducting a spacing element is transmitted, marking electron discharge devices connecmd to transmitting meansin such manner that when a device becomes conducting a marking element is.,

transmitted, connectonsqbetween said spacing and marking electron discharge devices constituting a chain of such devices forea'ch of said :code combinations, the numberofsaid devices for l the first element ofrsa-id code combinations being 7 Claims. (01. '1787) number of said devices for at least some of the succeeding elements being progressively halved, means for causing the devices in a chain to become conducting sequentially for equal periods of time and means for causing the initial device of a chain representing a selected code combination to become conducting.

The progressive halving of the number of devices maybe carried out for the whole series of elements, or it may be found convenient for certain purposes to carry out theprogressive halving fora certain number only of th elements.

If the invention is applied to the transmission of. a start-stop code so that each signal combinationconsists of a start element, a code combination of elements and a stop element, it is preferable to use a single electron discharge device for the transmission of the stop element of each signal combinationr There may be also a single electron dischargedevice for the start element of each signal combination, or it may be more convenient to use an electron discharge device individual to each signal combination for transmitting the start element thereof.-

The invention Will-be better understood from the following descriptionof certain embodiments thereof taken in conjunction with the accompanying drawings in Which-2 u Fig. 1 shows diagrammatically the arrangement of atransmitter,

" Fig. 2 shows part of the detailed circuits of the transmitter of Fig. 1,

Fig. 3 shows a modification of Fig. 1, Fig. 4 shows a modification of the circuits of part of Fig. 2 which may be used in-the transmitter of Fig. lor in'that of Fig. 2.

. "Referring to; the drawing, Fig. 1 shows a series of contacts I, one contact'for each charactento be transmitted. There'jare five rows 2' 6 of cold cathode gas filled tubes, each tube being allotted either to a spacing or marking code element of a signal. The tubes are represented by small circles, an open circle for a tube allotted 5 to a spacing element, a black circle for a tube allotted to a marking element. There are thirty two tubes in row 2; sixteen tubes in row 3, eight tubes in row 4, four tubes in row 5 and two tubes in row 6. The tubes in'each row are shown as O alternatelyspacing and marking and each pair .of; tubesin each row is connected to one tube in the next following row. Each contact i may then be taken as representing aparticular code combination of elements.

This contacts l are connected to a spacing tube: in row 2 and by follow- The tube 9 is normally ignited and the opera-' tion of transmitting a character is in outline as r follows:

Suppose a set of contacts of the row I, such as contacts 8 be closed. Contacts I I are closed, also, for example by means of a universal bar on the keyboard of a teletypewriter to which keys I belong. Assume a so arrangements are provided (which will be described in greater detail below) to cause the tubes of a selected combination to become ignited in sequence and that any tube becoming ignited causes the extinction of any other tube ignited. Then tube I 0 ignites followed after an interval by a tube in 'row 2 denoting a space, then the tube in row 3, denoting a mark, and so on until the required combination has been sent and. tube 9 becomes ignited to cause the sending of the stop element. Contacts II must be opened before tube 9 has been ignited for the full period of a i stop element, unless another of the contacts in row i has been operated. In this latter case the transmission of the neXt character continues immediately.

Fig. 2 shows the interconnections between the tubes required to send the characterrepresented by key 8 of Fig. 1, which is denoted again in Fig. 2 together with the tubes 9 and I0 and the contacts I I. The signals are sent over a line l2 connected over contacts 13 of a polarised telegraph relay I4 to either marking or spacing potential. Each tube is a three-electrode cold cathode tube having an anode, cathode and control electrode, and each tube causes the sending of a signal element of a particular character during the time it is ignited. To this end, the anodes of tubes such as tube I9, intended to send a spacing element, are connected over the spacing winding of relay I4, and a resistance to a positive potential source. The anodes of tubes, such as tube 9 intended to send a marking element are connected over the marking winding of relay l4 to the same positive potential source over the above mentioned resistance. The control electrode of each tube is connected over a condenser and resistance to a source of impulses I 5, which source produces a square pulse of short duration and approximately 40 volts positive every-:20 milliseconds.

The potential on the anode of each cold cathode tube when no discharge is passing in the tube is of such value that the tube becomes fired when the voltage between control electrode and cathode is between 70 and 80 volts. The cathode of each tube is connected to ground over a condenser and resistance in parallel so that when the tube has become ignited the condenser charges up and the potential drop across the resistance is about 80 volts.

Tube 9 being initially ignited, the sending of the character corresponding to the contacts '18 will be clear from Fig.2 and the following brief H description. Contacts II being close'd,'the midpoint of resistance I5, connecting the cathode of tube 9 to ground, is connected to the control elec- 4 trode of tube l9. Thus a bias of 40 volts positive is impressed between control electrode and cathode of tube I9. This is insufiicient to fire tube I9 but when an impulse from source I5 is added to this bias, tube I0 fires and causes current to flow through the tube and through the spacing winding of relay I4. The potential drop between anode and cathode of tube 9 when that tube is ignited is sufficiently low that the drop potential of the anode due to the increased current in the common impedance 39 is suflicient to extinguish tube 9. Contacts I3 change over to spacing to send the start element. The cathode of tube I0 is connected to ground over a resistanceand'condenser combination I1 and thereby a potential'of 40 volts positive is applied over contacts 8 to the control electrode of a tube I8. At the end of a period of 20 milliseconds during which a spacing element is sent to line [2 from contacts I3, an impulse from source I5 is applied over contacts 8 to the control electrode of tube I8 so that this tube I8 fires and tube II] is extinguished. As the anode of tube l8-is connected over the spacing winding of relay I4, contacts l3 remain in spacing position,-the first code element ofthe signal in the instance chosen for illustration being a spacing element.

'It will be noted from Fig. 1 that the tubes in row 2 are connected in pairs to the tubes in row 3, so that the control electrode of tube I9 in Fig. 2 may be biased either from the cathode of tube 18 or from the cathode of another tube 29. The cathodes of tubes I8 and 20 are connected to ground over respective condenser resistancecombinations "2| and 22 each giving a potential drop of about volts between cathode and ground when current passes through the corresponding tube. The cathodes of tubes I8 and 2a are connected over corresponding resistances 23 and 24 to the control electrode of tube I9.

When tube I8 is fired, current passes through the tube and through the resistance of combina' tion 2| to ground. Current also passes over resistances 23 and 24 and over the resistance of combinations 22 to ground. Resistances 23 and 24 are of such magnitude that the resultant bias on the control electrode of tube I9 when either tube I8 or tube 2Iiis fired is about 40 volts.

' Tube I8 remains fired until a further impulse from 'sourcel5 isapplied'to the control electrode of tube I9, i. e., forl'a period of twenty milliseconds. Tube l9 then fires and extinguishes tube I 8 by reason of the drop in potential in the comcession at intervals of about 20 milliseconds and that during the periods of 20 milliseconds during which current passes through tubes 25, 26, and 27 contacts [3 send space, mark and mark respectively to line I2. When tube 9 fires, marking potential remains connected to line l2 for the stop element of the signal.

Fig. 3 is a diagram reproducing the top half of Fig. 1 with certain modifications. The contacts I are contacts of individual relays denoted generally by reference 28 which may be operated selectively from any desired circuit or mechanism; Instead of a common start tube, individual start tubes II] for the various signal combinations are provided. In rank 6 of the tubes of the tree of tubes. Fig. 3 shows only two tubes 27a and 27b in this sixth rank for the lower half of the diagram oi Fig. 1. These tubes replace the single mark tube 21 of Fig. 1. Their outputs, together with the outputs of the two space tubes in rank 6 are common to a tube 9 which acts as the stop tube. closed whenever one of the relays 28 is operated.

If, in the arangement shown in Fig. 1 or Fig. 2

any actuated key is held depressed too long or any of the relays 28 remains energised too long there is a danger that contacts ll may remain closed when tube 9 has fired and for milliseconds thereafter, in which case the start tube 10 may fire. This would result either in a repetition of the preceding character or mutilation of a succeeding character.

Fig. 4 shows a modification of Fig. 2 whereby such disturbance may be avoided. Fig. 4 shows only such part of Fig. 2 as is necesasry for understanding the modifications now to be described. v

The contacts I I of Fig. l, are now replaced by'two contacts 3| and 32. Contacts 3| are contacts of a relay 33. Each character key has two sets of contacts which it closes when operated, one set such as 8 which causes a bias to be applied to the control electrode of the first tube, such as M, in the chain of tubes, and another set 34, insulated from 8, which closes the circuit of relay 33. Relay 33 then closes its contacts 3| and connects the cathode circuit of the stop tube 9- to the start tube Hi; It will be seen from the drawing that this last-mentioned connection is taken also over normally closed contacts 32. Thus when a key is actuated the transmission of the start elementof the signal commences when the first pulse from the source l5 of Fig. 2 occurs.

When the tube [0 for transmitting the start element fires, a bias is applied fromits cathode circuit-l1 to the first tube in the required chain of tubes, such' as tube l8, over contacts, such as Contacts II are 8 of the key and also to an auxiliary tube 35.

Accordingly, when the next succeeding pulse occurs, tube l8 fires to cause the transmission of the first code element of the signal and tube mon to the anode circuits of all the tubes in the transmitter. In consequence of this common impedance, when the cathode of tube 35 has reached a voltage above that of ground by the charging up of the condenser 49, and a further tube fires on a succeeding impulse from source I5, tube 35 is extinguished.

. Relay 38 remains operated in its locking circuit until the operated key has been released. When this occurs relay 33 is de-energized, opening contacts 38 and 3! and opening the circuit of relay 36 which thereupon recloses contacts 32. until the operated key has been released and the same or another key re-operated.

Similar circuits to those of Fig. 4 may be used with the arrangement of Fig. 3.

Further modifications oi. the circuits so far Thus the start tube I ll cannot be fired again described will be apparent to those skilled in the art. Thus a bias applied to a plurality of tubes may be applied through rectifiers in such manner as to prevent a bias passed back from one to another of the plurality of tubes.

Further the marking and spacing windings of the transmitting relay M could be connected in the cathode circuits of therespective tubes instead of in the anode circuits as shown.

While the principles of the invention have been described above in connection with specific examples and particular modifications thereof, it is to be clearly understood that this description is made only by way of example and not as a limitation on the scope of the invention.

What is claimed is:

1. A transmitter for transmitting any one of a plurality of code combinations each consisting of the same number of successive elements of marking or spacing condition comprising transmitting means, a plurality of spacing electron discharge devices connected to said transmitting means in such manner that when any of said spacing devices becomes conducting a spacing element is transmitted by said transmitting means, a plurality of marking electron discharge devices connected to said transmitting means in such manner that when any of said marking devices becomes conducting a marking element is transmitted over said transmitting means, connections between said spacing and marking electron discharge devices constituting a chain of such devices for each of said code combinations, the number of said devices for the first element of said code combinations being equal to the number of such combinations but the number of said devices for at least some of the succeeding elements being progressively halved, means for causing the devices in a chain to become conducting sequentially for equal periods of time and means for causing the initial device of a chain representing a selected code combination to become conducting.

2. A transmitter as claimed in claim 1 in which the means for causing the initial device of a chain to become conducting comprises contacts individual to an electron discharge device 'for the first element so connected to said device as to bias said device towards conductivity.

3. A transmitter as claimed in claim 2 for a start-stop code comprising a single start electron discharge device for transmitting the start element of a code combination, a single stop electron discharge device for transmitting the stop element of all code combinations and norreally in a conducting condition contacts common to all code combinations for connecting said stop device to said start device in a chain of such devices and contacts individual to the respective code combinations for connecting said start device to the first device of a chain of such devices representing the required code combination of such devices.

4;. A transmitter as claimed in claim 6 wherein each of said electron discharge devices is a three-electrode cold cathode gas filled tube.

5. A transmitter for transmitting any one of a plurality of code combinations each consisting of a marking or spacing condition, comprising a source of operating potential, transmitting means, a plurality of spacing electron discharge devices connected to said transmitting means in such manner that when any of said spacing devices become conducting a spacing element is transmitted :by said transmitting means, a plurality of marking electron discharge devices connected to said transmitting means in such manner that when any of said marking devices becomes conducting a marking element is transmitted by said transmitting means, connections between said spacing and marking discharge devices constituting a chain of such devices for each of said code combinations, the number of said discharge devices for the first element of said code combinations being equal to the number of such combinations but the number of said devices for at least some of the succeeding elements being progressively halved, a single start electron discharge device connected. to said transmitting means for transmission of the start element of each code combination, individual contact means for selectively coupling said start device with selected of the devices representing the first element of a predetermined code combination, said contact means adapted to bias a selected of said last-named devices toward conductivity, a single step electron discharge device connected to said transmitting means for transmission of the stop element of each code combination, said stop device coupled to each of the ultimate devices of said chains, additional contact means operable with any of said individual contact means for coupling said stop device to said startdevice, said last named contact means adapted to bias said start device toward conductivity, means for causing said start device and the devices in a selected chain to become conducting sequentially for equal periods of time, said last named means adapted to maintain said stop device in a normally conducting condition, and means connected between said source and said transmitting means for extinguishing any of said devices which have been rendered conductive upon the rendering conductive of any other of said devices, whereby a start element, marking and spacing elements of a selected code combination, and a stop element are transmitted by said transmitting means.

6. A transmitter as claimed in claim wherein said additional contact means further comprises two pairs of contacts in series, a first pair of said contacts adapted to be initially open and adapted to be closed when any of said individual contact means are closed, the other pair of said contacts adapted to be initially closed but opened after the transmission of an initial element of any code combination, whereby transmission of a second code combination cannot commence until release of any closed of said individual contact means.

'7. A transmitter as claimed in claim 6, wherein said additional contact means comprises an auxiliary electron discharge device, switch means adapted to be operated simultaneously with any of said individual contact means, a pair of relays each having energizing windings, the first of said relays having two pairs of front contacts, and

the other of said relays having a pair of front contacts and a pair of back contacts, the winding of said first relay and said switch means serially connected across said source, the winding of said second relay, the discharge path of said auxiliary device and said extinguishing means serially connected across said source, one pair of front contacts of said first relay and the back contacts of said second relay serially disposed between said start device and said stop device, the other pair of front contacts of said first relay and the pair of front contacts of said second relay serially connected between said source and the junction of said auxiliary discharge device with said second relay winding, said auxiliary discharge device coupled to said start device and adapted to be biassed toward conductivity thereby and further coupled to said means for causing said devices to become conducting.

.ROLAND HARRIS DUNN.

FREDERICK WILLIAM WARDEN.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,900,954 Sandeman Mar. 14, 1933 2,361,766 Hadekel Oct. 31, 1944 FOREIGN PATENTS Number Country Date 344,444 Great Britain Feb. 27, 1931 

